WO1997027222A1 - Verfahren zur herstellung einer wässrigen polymerisatdispersion nach der methode der radikalischen wässrigen emulsionspolymerisation - Google Patents
Verfahren zur herstellung einer wässrigen polymerisatdispersion nach der methode der radikalischen wässrigen emulsionspolymerisation Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2/00—Processes of polymerisation
- C08F2/12—Polymerisation in non-solvents
- C08F2/16—Aqueous medium
- C08F2/22—Emulsion polymerisation
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F297/00—Macromolecular compounds obtained by successively polymerising different monomer systems using a catalyst of the ionic or coordination type without deactivating the intermediate polymer
- C08F297/02—Macromolecular compounds obtained by successively polymerising different monomer systems using a catalyst of the ionic or coordination type without deactivating the intermediate polymer using a catalyst of the anionic type
- C08F297/026—Macromolecular compounds obtained by successively polymerising different monomer systems using a catalyst of the ionic or coordination type without deactivating the intermediate polymer using a catalyst of the anionic type polymerising acrylic acid, methacrylic acid or derivatives thereof
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/02—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques
- C08J3/03—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques in aqueous media
Definitions
- the present invention relates to a process for the preparation of an aqueous polymer dispersion by polymerizing monomers having at least one vinyl group according to the
- Free-radical aqueous emulsion polymerization method in which an amphiphilic substance is added to the polymerization vessel before and / or during the polymerization.
- Aqueous polymer dispersions are generally known. These are fluid systems which, as a disperse phase in an aqueous dispersion medium, contain polymer balls (so-called polymer particles) consisting of a plurality of intertwined polymer chains (so-called polymer particles) in disperse distribution.
- the diameter of the polymer particles is often in the range from 10 nm to 2000 nm.
- aqueous polymer dispersions have the potential to form polymer films when evaporating the aqueous dispersing medium, which is why they are used in particular as binders, e.g. for paints or for masses for coating leather, paper or plastic films. Because of their environmentally friendly properties, they are becoming increasingly important.
- aqueous polymer dispersions An important feature of aqueous polymer dispersions is the diameter of the polymer particles in disperse distribution, since a number of technical properties of aqueous polymer dispersions are determined by the size of the polymer particles or by their size distribution. For example, films made from finely divided aqueous polymer dispersions have an increased gloss (cf. e.g. Progress in Organic Coatings 6 (1978), p. 22). Furthermore, that is
- Aqueous polymer dispersions whose polymer particle diameters are distributed over a larger diameter range also have an advantageous flow behavior (cf. e.g. DE-A 42 13 965).
- a central role in the production of an aqueous polymer dispersion is therefore the targeted, reproducible adjustment of the diameter of the dispersed polymer particles, which is tailored to the respective intended use.
- the most important method for the preparation of aqueous polymer dispersions is the radical emulsion polymerization method, in particular the free radical aqueous emulsion polymerization.
- At least one monomers having a vinyl group are typically polymerized radically under the action of free-radical polymerization initiators dissolved in the aqueous medium to polymer particles which are dispersed directly in the aqueous dispersing medium.
- the aqueous polymer dispersions prepared by the free-radical aqueous emulsion polymerization method are usually also referred to as aqueous primary dispersions in order to distinguish them from the so-called aqueous secondary dispersions.
- the polymerization takes place in a non-aqueous medium. Dispersion into the aqueous medium takes place only after the polymerization reaction has ended.
- the monomers to be polymerized are distributed in droplets in an aqueous medium to form an aqueous monomer emulsion (the droplet diameter is often 2 to 10 ⁇ m).
- these monomer droplets do not form the polymerization sites but only act as a monomer reservoir. Rather, the formation of the polymerization sites takes place in the aqueous phase, which always contains a limited proportion of the monomers to be polymerized and the free radical polymerization initiator in solution.
- the chemical reaction of these reaction partners in solution leads to the formation of oligomer radicals, which precipitate as primary particles above a critical chain length (homogeneous nucleation).
- the formation of primary particles probably takes place up to that Point at which the rate of formation of radicals in the - aqueous phase is as great as the speed of their disappearance as a result of the radical capture by already formed polymer particles.
- the polymer particle growth phase then follows this polymer particle formation phase. Ie, from the monomer droplets acting as reservoirs, the monomers to be polymerized diffuse via the aqueous phase to the primary particles formed (the number and surface area of which is very much larger than that of the monomer droplets) in order to be polymerized into the same (see, for example, fiber research and Textiltechnik 28 (1977), No. 7, Journal for Polymer Research p. 309).
- suitable dispersants both the disperse distribution of the monomer droplets and the disperse distribution of the polymer particles formed are optionally stabilized.
- polymer particle formation is essentially a stochastic process.
- the number of polymer primary particles formed and thus the diameter of the polymer end particles ultimately resulting after the end of the polymerization fluctuate from the polymerization batch to the polymerization batch.
- the product quality fluctuates in a corresponding manner (identical reproduction normally does not succeed).
- This is particularly true with an increased solids volume content (> 50% by volume) of the aqueous polymer dispersion, since e.g. the viscosity of highly concentrated aqueous polymer dispersions depends in a particularly sensitive manner on the number and size of the polymer particles contained in dispersed form.
- amphiphilic of said case, that both surfactants have ⁇ hydrophilic and hydrophobic groups. Hydrophilic groups are those which are drawn into the aqueous phase, while hydrophobic groups are forced out of the aqueous phase.
- surfactants are therefore essentially molecularly dissolved as mutually independent molecules, their amphiphilic structure necessitating an accumulation on the water surface as oriented adsorption, which brings about a reduction in the surface tension.
- surfactants are predominantly in micellar solution.
- the surfactant molecules in the aqueous solution predominantly arrange themselves into higher aggregates, so-called micelles, in which they are oriented so that the hydrophilic groups face the aqueous phase and the hydrophobic groups point inside the micelle. If the surfactant concentration is increased further, essentially only the number of micelles in the volume unit increases, but not that of the molecularly dissolved surfactant molecules per volume unit.
- micellar solution is intended to express that the optical appearance of a micellar aqueous surfactant solution, like that of a molecular aqueous surfactant solution, is that of a clear aqueous solution.
- the relative molecular weight of surfactants is normally ⁇ 2000 and in their micellar aqueous solutions there is usually a rapid exchange (a dynamic equilibrium) between the various molecular and micellar dissolved surfactant components.
- the following are typical examples of surfactants (source: Ullmanns Encyclopedia of Technical Chemistry, Verlag Chemie, 4th edition, vol. 22, pp. 456 ff):
- the surface tension of pure water is 73 mN / m at 20 ° C and 1 atm.
- surfactant micelles in aqueous medium form the nucleus for the formation of polymer primary particles (this is also referred to as micellar nucleation). If the free-radical aqueous emulsion polymerization is dissolved, e.g. in the presence of a large number of surfactant micelles, many small polymer end particles are obtained, while a few large polymer end particles result when released in the presence of a small number of surfactant micelles.
- the surfactant generally reduces both the interfacial tension "polymer particles / aqueous medium” and the interfacial tension "monomer droplets / aqueous medium” and is thus able to stabilize the respective disperse distribution as a dispersant, which is advantageous for free-radical aqueous emulsion polymerization affects.
- the disadvantage is usually the decrease in surface tension caused by the surfactant, which increases the tendency to foam.
- EP-B 40 419 e.g. p. 5, lines 16 ff and Example 1
- DE-A 23 21 835 e.g. p. 14, lines 9 ff
- p. 847 therefore recommend polymer particle formation to adjust the final polymer particle size. phase and the polymer particle coupled to one another corresponds _.
- a defined amount of a separately pre-formed aqueous polymer dispersion is added and the polymer particles contained in this seed are only allowed to grow in the course of the actual free-radical aqueous emulsion polymerization .
- the diameter of the seed polymer particles and the quantitative ratio of the seed polymer particles and monomers to be polymerized essentially determine the size of the polymer end particles in the resulting aqueous polymer dispersion. The more finely divided the seed and the greater the amount of seed used, the smaller the resulting polymer particles for a given amount of monomer.
- the aim is to achieve a broad distribution of the diameter of the polymer particles, additional seed polymer dispersion is added to the polymerization vessel even during the free-radical aqueous emulsion polymerization of the monomers.
- the resulting aqueous polymer dispersion comprises different generations of seed polymer particles which have grown to a different final size.
- a similar effect can also be produced by causing micelle formation in the course of the free radical aqueous emulsion polymerization of the monomers by increased addition of surfactant.
- a disadvantage of the method of free-radical aqueous emulsion polymerization with the addition of an aqueous seed polymer dispersion is, however, that the aqueous seed polymer dispersion must be stored before use, which is due to the basic sensitivity of aqueous polymer dispersions (they strive for their interface to reduce) against frost, shear, drying and vibration is often problematic.
- an identical product manufacture at different production sites requires the corresponding identical availability of such an aqueous seed polymer dispersion.
- An additional problem is the reproducible production of an aqueous seed polymer dispersion.
- the object of the present invention was therefore to provide a process for the preparation of an aqueous polymer dispersion by polymerizing monomers having at least one vinyl group by the free-radical aqueous emulsion polymerization method, which method is comparable in quality to the seed procedure a controlled implementation of the radical aqueous emulsion polymerization enables, but does not have the disadvantages of seed storage.
- 1 1 water at 20 ° C and 1 atm is able to absorb at least 10 ' 4 mol of the amphiphilic substance in micellar solution;
- the critical micelle formation concentration of the amphiphilic substance at 20 ° C and 1 atm in water is ⁇ 10 " 6 mol / 1 and
- the surface tension ⁇ of an aqueous molecular and / or micellar solution of the amphiphilic substance in the molar concentration range (0 ⁇ C M ⁇ 10- 4 ) mol / l at 20 ° C and 1 atm does not fall below 60 mN / m.
- the CMC according to the invention to ver ⁇ -inverting amphiphilic substance at 20 ° C and 1 atm in water ⁇ IO "6-25 mol / 1, more preferably ⁇ IO" 6-5 mol / 1, particularly preferably
- the surface tension ⁇ of an aqueous molecular and / or micellar solution of the amphiphilic substance to be used according to the invention in the molar concentration range (0 ⁇ C M ⁇ 10- 4 ) mol / l at 20 ° C. and 1 atm the value 62.5 mN / m, preferably the value 65 mN / m, particularly preferably the value 67.5 mN / m, very particularly preferably the value 70 mN / m and even better not less than the value 71.5 mN / m .
- the aforementioned values are preferably not undercut even until a molar concentration of IO ' 3 mol / 1 is reached.
- amphiphilic substance to be used according to the invention is such that 1 liter of water at 20 ° C. and 1 atm at least IO " 3 mol, preferably at least IO " 2 mol and particularly preferably at least 10 "1 mol or 1 mol of the amphiphilic substance in micellar solution is able to absorb.
- the basis of the present invention is the observation that it is not only surfactants, ie low-molecular amphiphilic substances, which significantly reduce the surface tension of the water. wrestle, are capable of forming micellar aqueous solutions above a cmc, but that this property can essentially be ascribed to amphiphilic substances in general.
- the c.m.c. is essentially determined by the nature of the hydrophobic groupings of the amphiphilic substance, the c.m.c. with increasing expansion (e.g. increasing length (number of carbon atoms) of the alkyl group) the hydrophobic group takes on lower values.
- the influence of the hydrophilic grouping on the c.m.c. in contrast, is comparatively small.
- amphiphilic substances to be added according to the invention are those whose proportion in molecularly dissolved form in their micelle aqueous solution is particularly low and in which the exchange between the various micellar or molecularly dissolved substances is present Shares in their micellar aqueous solutions are particularly slow (increased kinetic stability).
- micellar aqueous solutions of the amphiphilic substances to be added according to the invention are now particularly suitable as germ sites for controlled implementation. tion of radical aqueous emulsion polymerizations of at least one vinyl group-containing monomers.
- micellar aqueous solutions of the classic surfactants are probably as follows. If, in the presence of classic aqueous micellar systems, polymer particle formation is triggered in some micelles with the start of free radical aqueous emulsion polymerization, other micelles which have not yet been initiated begin to dissolve (due to the rapid exchange) in order to help stabilize the surface of the growing polymer particles, thereby the quantitative relationship between the original number of micelles and the number of polymer particles formed is lost.
- micellar resolution decreases in the course of the formation of the polymer particles and the polymer particle formation phase approaches the limit case in which each micelle originally present becomes the nucleus of a polymer particle (with increasing kinetic stability of the mi ⁇ cellen usually also grows their stability against the addition of foreign electrolyte).
- an aqueous micellar solution can increasingly act on the course of a free radical aqueous emulsion polymerization like an aqueous seed polymer dispersion. In contrast to the latter, however, it can be produced in a reproducible manner and stored dry, which excludes the disadvantages of storing seed polymer dispersion.
- the desired micellar effect of the amphiphilic substance to be added according to the invention can be produced in the course of a free radical aqueous emulsion polymerization by adding the amphiphilic substance to the aqueous polymerization medium as such in a solution above the c.m.c. lying quantity adds.
- the amphiphilic substance to be added according to the invention will be added in the form of a pre-formed micellar solution (both water and a water-miscible organic solvent or a mixture of water and such a solvent are suitable as solvents).
- micellar aqueous solution is often achieved by firstly adding the amphiphilic substance to be added according to the invention in an organic miscible with water Solvents or in a mixture of water and such - ' organic solvent molecularly and / or micellarly dissolves (for example in dioxane, tetrahydrofuran or their mixtures with water) and this molecular and / or micellar solution (which according to the invention often also directly into the aqueous polymerization medium can be added) then, for example, via dialysis or multiple additions of small amounts of water and subsequent separation of the organic solvent used by distillation into an aqueous micellar solution (instead of water, an aqueous solution of an acid and / or base is often also used) and the same, if appropriate concentrated by evaporation of
- Aqueous micellar solutions produced in this way at 1 atm and 20 ° C. are generally not in thermodynamic equilibrium. However, they are normally of increased kinetic stability, ie the micelles contained therein behave like quasi-molecular structures between which there is virtually no exchange.
- the average residence time of an amphiphilic molecule in such micelles can extend to several hours or days, even at elevated temperatures.
- the extent to which such aqueous micellar solutions still have a cmc must be left open in many cases. If so, it is at very low concentrations.
- aqueous micellar solutions which can usually only be produced directly and are not in thermodynamic equilibrium, are frequently referred to in the literature as solutions of "frozen" micelles (cf., for example, Polymer Preprints 32 (1), 525 (1991) , Macromol. Chem. Macromol. Symp. 58, 195-199 (1992) or Langmuir 1993, 9, 1741-1748). They generally do not change their macroscopic appearance over several days (at 20 ° C and 1 atm). On the way of the direct solution of amphiphilic substances, aqueous micellar solutions of corresponding kinetic stability are rarely available.
- aqueous solutions of "frozen" micelles of amphiphilic substances to be added according to the invention can be used instead of aqueous seed polymer dispersions for the controlled implementation of free-radical aqueous emulsion polymerizations (they can be added as such or, under certain circumstances, can also be generated in situ in the aqueous polymerization medium in which For example, a solution of the amphiphilic substance to be added according to the invention in a water-miscible organic solvent is added to the aqueous polymerization medium).
- aqueous micellar solutions can be produced and used according to the invention because of their kinetic stability Concentration of amphiphilic substance below whose cmc _ is.
- the surface tension of the aqueous solutions of the amphiphilic substances to be added according to the invention is no longer a suitable measured variable.
- the c.m.c. used in this document Information therefore relates to studies of the concentration dependence of the scattering behavior (Classical Light Scattering From Polymer Solutions, Pavel Kratochvil, Elsevier, New York (1987), in particular Chapter 2.1.2) of the relevant aqueous solutions (classic light scattering; Price, C. Pure Appl. Chem. 1983, 55, 1563; Price, C; Chan, EKM; Stubbersfield, RB Eur. Polym. J. 1987, 23, 649 and Price, C; Stubbersfield, RB; El-Kafrawy, S. ; Kendall, KD Br. Polym. J. 1989, 21, 391) or, insofar as the sensitivity of this test method is not sufficient, to studies of the fluorescence behavior of hydrophobic dyes such as fluorol 7GA or pyrene, which are found in the hydrophobic
- Block polymers of which at least one of the contained blocks (hydrophilic group) as a stand-alone polymer is very good and at least one of the contained blocks (hydrophobic grouping) as a stand-alone polymer is only slightly water-soluble, form a particularly clear type of amphiphilic substances.
- block polymer stands for polymers whose molecules (instead of the term molecule in connection with micelle-forming amphiphilic substances, the more general term "unimer” is often used in the literature to conceptually differentiate the individual species from their micellar aggregation, since the term molecule, strictly speaking, does not include, for example, polyelectrolyte types) consist of, preferably linear, linked blocks, the blocks being direct or constitutional Units which are not part of the blocks are connected to one another " and the term block means a section of a polymer molecule (unimers) which comprises several identical constitutional units and has at least one constitutional or configurative characteristic which is immediately apparent in the adjacent sections does not occur. Di-block polymers accordingly consist of two blocks.
- Block polymers can be obtained in a simple manner by first successively linking one type of monomeric building blocks to one another, then continuing this linkage with another type of monomeric building block, subsequently possibly carrying out further changes in the monomeric building block type and so on Required di-, tri- and higher block polymers.
- the linkage can be carried out both within the individual block and between the blocks, e.g. are carried out in a manner known per se by initiated polymerization (keyword: “living polymers”; see, for example, Ulimanns Encyklopadie der Technische Chemie, vol. 13, 4th edition, Verlag Chemie, New York, p. 599).
- the initiated polymerization is designed in a manner known per se in such a way that after complete consumption of a monomer type, either macroinitiators which are still active or which can be reactivated by suitable measures are obtained and continue to grow after the addition of the next monomer type until theirs Activity is deliberately deleted by adding suitable inhibitors.
- a particularly frequently used method of such an initiated sequential polymerization is the sequential anionic polymerization (cf. for example US Pat. No. 3,251,905; US Pat. No. 3,390,207; US Pat. No. 3,598,887; US Pat. No. 4,219,627; Macromolecules 1994, 27, 4908; Polymer, 1991, Volume 32, Number 12, 2279; Macromolecules 1994, 27, 4615; Macromolecules 1994, 27, 4635 and Macromolecules 1991, 24, 4997). It proceeds like the radical-initiated polymerization according to the chain reaction scheme. However, the initiator is not a starter radical, but rather a starter anion that transfers its charge to the growing macromolecule, which in turn can act as a starter anion and continue to grow. If the starting reaction is very fast compared to the growth reaction, very narrow molecular mass distributions are available.
- a monomer having at least one ethylenically unsaturated group cannot be polymerized anionically, the procedure can be modified in such a way that polymerization is initiated, for example, with free radical or cationic initiation.
- polymerization is initiated, for example, with free radical or cationic initiation.
- blocks produced by anionically initiated polymerization to blocks which can only be obtained by polycondensation or polyaddition of monomeric building blocks (for example polyesters or polyurethanes) by, for example, an anionically produced block provided with a suitable functional end group Block is added in a polycondensation (for example RN Young, RP Quirk, LJ Fetters, Advances in Polymer Science, Vol. 56, p. 70, 1984).
- RN Young, RP Quirk, LJ Fetters Advances in Polymer Science, Vol. 56, p. 70, 1984.
- Wilhelm, M. et al. Macromolecules, 1991, 24, 1033 concerns e.g. Polystyrene-polyethylene oxide di-block polymers.
- the production of block polymers by radical polymerization using functional initiators or macroinitiators is described, for example, by B. Riess, G. Hurtrez, P. Bahadur in "Encyclopedia of Polymer Science and Engineering", Vol. 2, 327-330
- block polymers can be produced from block polymers by subsequent chemical reactions (e.g. polymer-analogous reactions).
- Di-block polymers which can be obtained by anionic sequential polymerization of first an alkyl ester of methacrylic acid and then glycidyl methacrylate and then converting the oxiranyl groups into ⁇ -hydroxysulfonate groups.
- Macromolecules 1993, 26, 7339-7352 discloses e.g. the production of polystyrene-polyacrylic acid di-block polymers by hydrolysis of polystyrene-poly (tert-butyl acrylate) di-block polymers.
- EP-A 665 240 describes poly-methacrylate-polymethacrylic acid di-block polymers in which the two blocks are constituted by a constitutional unit CH 3
- block polymers can be symbolized in a simple manner by placing the basic unit of the respective block in square brackets and with one outside the The number enclosed in square brackets shows how often the basic unit is contained in the respective block linked to itself.
- the sequence of the square brackets can be used to reproduce the chronological sequence of the block production.
- amphiphilic block polymers dissolved in water can act like conventional surfactants if the hydrophobic and hydrophilic blocks contained are of suitable length, which is why they are also referred to as polymeric surfactants and, inter alia, are recommended as dispersants for stabilizing aqueous polymer dispersions.
- EP-A 665 240 recommends di-block polymers
- Macromolecules 1991, 24, 5922-5925 shows that when an aqueous solution of the aforementioned di-block polymers is added to an aqueous standard polymer dispersion (in a polymerization vessel) a mixture of 20 g of ethyl acrylate, 80 g of water, 100 mg of K 2 S 2 O ⁇ and 0.02 g of sodium oleyl tauride sulfonate is introduced with stirring (150 revolutions per minute) and freed from oxygen by means of a stream of nitrogen; the mixture is then heated to 80 ° C. 5 and the mixture is kept at this temperature and stirring is maintained for 30 minutes.
- the resulting mean polymer particle diameter is 80 nm (photon correlation spectroscopy)), which quickly draws the di-block polymer onto the surface of the dispersed polymer particles 10 (increase in the hydrodynamic radius of the dispersed polymer particles determined by means of photon correlation spectroscopy) and enables the dispersed distribution to be stabilized.
- amphiphilic substances are added as IO -3 molar micellar aqueous solution to the aforementioned aqueous standard polymer dispersion (in a total amount of 3% by weight of amphiphilic substance, based on the dispersed polymer).
- the mean residence time of a unimer in a micelle can be determined in a manner known per se, for example, by marking an amphiphilic unimer type in two different ways, and producing two separate aqueous micellar solutions from the differently labeled unimers. contain differently labeled micelles, mix these solutions ⁇ and then observe the time-dependent setting of an aqueous micellar solution of micelles having a mixed label.
- a simple way of labeling is to covalently label the hydrophobic grouping with two different fluorophores, the two fluorophores being selected such that when they approach a distance of ⁇ 10 nm, the fluorescence decay of one (donor) by radiation unscrupulous energy transfer (Förster transfer) to the other (acceptor) is shortened.
- micellar solution the unimers of which are exclusively donor-labeled in the aforementioned manner
- aqueous micellar solution the unimers of which are exclusively acceptor-labeled in the aforementioned manner
- the two solutions are subsequently mixed
- Unimer exchange Micelles which contain both donor and acceptor-labeled unimers at a distance of ⁇ 10 nm, since the hydrophobic groupings point inside the micelles.
- the change over time in the fluorescence decay of the donor fluorophore as a function of this exchange provides the mean residence time in a manner known per se.
- the end value of the fluorescence decay can be determined by first dissolving a mixture of donor- and acceptor-labeled unimers in an organic solvent, the solvent e.g. separated by distillation and the required aqueous micellar solution produced from the resulting powder, the micelles of which then contain both donor- and acceptor-labeled unimers from the beginning (cf.Förster, Zeitschrift für Naturforschung, Vol. A4 (1949), 321; The synthesis of polymers bearing terminal fluorescent and fluorescence-quenching groups in Macromol. Chem., 191 (1990), 3069; Langmuir 1993, 1741-1748; Macromol. Chem. Macromol. Symp. 58 (1992), 195-199; Collect. Czech Chem. Commun. (Vol. 58), (1993), 2362; Macromolecules 1992, 25, 461-469).
- micellar aqueous solutions of the amphiphilic substances to be added according to the invention is particularly the rate of migration in the centrifugal field of the analytical ultracentrifuge (AUZ.).
- AUZ. analytical ultracentrifuge
- two micellar types of different masses are known in the AUZ sedimentation run (see, for example, W. Mächtle in SE Harding et al (Ed.) "Analytical Ultracentrifugation in Biochemistry and Polymer Science", Royal Society of Chemistry, Cambridge, England (1992 ), Chap.
- the area un ⁇ is proportional to the respective peak of the respective absolute amount. If, as a function of time, the two micellar types of different masses merge to form a micellar type of medium mass, the two aforementioned Schlieren peaks and a third Schlieren peak disappear as a function of time.
- the time characteristic provides the desired average residence time in a manner known per se.
- the AUZ sedimentation run is able to show the unimerically dissolved portion contained in the micelle aqueous solutions of the amphiphilic substances to be added according to the invention.
- amphiphilic substances are preferred, in their micellar aqueous solutions in the concentration range from IO " 4 mol / 1 to IO 3 mol / 1 (if accessible) at 20 ° C and 1 atm the unimer dissolved proportion, based on the total dissolved amount of amphiphilic substance,
- amphiphilic substances to be added according to the invention can now be obtained by adding the number of basic units contained in the hydrophobic blocks (the length or the extension) of the hydrophobic block) is increased and at the same time the length of the hydrophilic blocks is dimensioned such that they enable the micelle assembly to be dissolved.
- the associated loss of surfactancy is erfindungs-- 'of substantially disregarded because aim of the invention is an insert as quasi aqueous seed polymer dispersion.
- the dominant influence of the expansion of the hydrophobic block is e.g. based on the c.m.c. aqueous solutions of di-block polymers of the general formula
- the group of amphiphilic substances to be added according to the invention therefore includes, in particular, di- and tri-block polymers of the general formulas I, I ', II [A] a [B] b (D ⁇ t B ⁇ b tA] a (I '), and [A] a' [B] b [A] a - *> zw - [A] a . [B] b [A '] a r. (II),
- B a basic unit from the group comprising styrene
- a (A ') a basic unit from the group comprising 3 to 6 carbon atoms containing ⁇ , ⁇ -monoethylenically unsaturated
- Mono- and dicarboxylic acids 2-acrylamido-2-methylpropane sulfonic acid, styrene sulfonic acid, vinyl sulfonic acid and the alkali metal (especially Na and K) - and ammonium salts of the aforementioned acids, N-vinyl pyrrolidone, vinyl alcohol, ethylene glycol and propylene glycol.
- both the A (A ') and the B block can also be copolymers of the corresponding degree of polymerization from the monomers of the respective group (this statement also relates to the groups highlighted below as preferred).
- B is preferably a basic unit from the group comprising styrene, methylstyrene, chlorostyrene, vinyl acetate, vinyl propionate, methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate and methyl methacrylate.
- B is particularly preferably a basic unit from the group comprising styrene, methyl methacrylate, n-butyl acrylate and 2-ethylhexyl acrylate.
- the B block is very particularly preferably composed of styrene and / or methyl methacrylate.
- a (A ') is preferably a basic unit from the group comprising acrylic acid, methacrylic acid, vinylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid and the Na, K and NH 4 salts of these acids.
- the A (A ') block is particularly preferably composed of acrylic acid, methacrylic acid and / or their K, Na, NH 4 salts.
- b is generally an integer> 30, preferably> 35, particularly preferably> 40 and very particularly preferably> 45 or> 50 (in the case of non-uniform molecular weights Block polymers the statements given here refer to the number-average values of the coefficients b, a, a 'and a'').
- Favorable di-, tri-block polymers of the general formulas I, II are also those with b> 75 or b> 100.
- b will be ⁇ 1000 or ⁇ 800, mostly ⁇ 600 and often ⁇ 400.
- the range b 30 30 to 40 is also of particular interest, since its applications enable the production of finely divided aqueous polymer dispersions. This is particularly true if the basic units for blocks A (A ') and B are recruited from the particularly preferred groups.
- Block B was chosen with regard to its monomer composition and its length such that it has, as an independent polymer, a glass transition temperature Tg 20 20, preferably> 40, particularly preferably> 60, very particularly preferably> 80 and even better> 100 ° C.
- Tg means the quasi-static glass transition temperature measured by DSC (differential scanning calorimetry, 20 ° C / min., Midpoint) according to DIN 53765.
- the upper limit values for Tg in the case of high molecular weights and homopolymeric blocks B are e.g. Tab. 8 in Ullmann's Encyclopedia of Industrial Chemistry, VCH, Weinheim (1992), Vol. A21, p.169.
- micellar solubilization in aqueous solution required according to the invention is possible in the case of the di-block polymers I when a is at least 40% or at least 50% of b.
- a is at least 75% of b and often applies a> b. a values of up to 2500 and more are possible.
- micellar solubilization in aqueous solution required according to the invention is usually possible when a 'and a' 'independently of one another are at least 20% and at least 25% of b. As a rule, they are at least 40% of b and frequently apply a ', a' '> b / 2 or> b. a ', a' 'values of up to 2000 and more are possible.
- micellar aqueous solution generally changes into a molecular aqueous solution.
- a direct micellar aqueous solution of the di- and tri-block polymers of the general formulas I, II is often possible when the basic unit A is the salt of a mono-ethylenically unsaturated organic acid.
- the basic unit A on the other hand to the free acid, has generally the path of the indirek ⁇ th loosening (initially dissolved in a mixture of water and an organic solvent, wherein a last is chosen with advantage so that the block B would be soluble as an independent polymer in this solvent then successively displacing the organic solvent via dialysis and / or adding water in combination with distillative solvent separation).
- the direct micellar dissolution of the free acid in alkaline water is also often successful.
- preferred amphiphilic substances to be used according to the invention are those di- and tri-block polymers of the general formulas I, II, the hydrophilic blocks A of which are polyelectrolytic in nature (ie not non-ionic, but dissociating into a polyion and counterions in an aqueous medium) .
- micellar aqueous solutions of the amphiphilic substances to be added according to the invention solubilize, according to the radical aqueous emulsion polymerization method, monomers to be polymerized, which have at least one vinyl group, more selectively than the micellar aqueous solutions of the classic surfactants. That is, when they are used for the controlled implementation of free-radical aqueous emulsion polymerizations, it is advisable to match the hydrophobic micellar core and the monomers to be polymerized, i.e. choose chemically similar to each other. Accordingly, hydrophobic blocks B containing the element fluorine are less preferred according to the invention.
- block polymers I, II suitable as amphiphilic substances to be added according to the invention are listed below.
- a d in brackets indicates that the route of direct dissolution has been chosen to obtain the at least 10 " 4 molar micellar aqueous solution, while a corresponding i followed indirect solubilization (generally starting from dioxane / water Mixtures) shows: [Styrene] 260 [methacrylic acid] 385 (i) [styrene] 381 [methacrylic acid] 3 20 (i) [styrene] 233 [methacrylic acid] 24 o (i) [styrene] 333 [methacrylic acid] 2 68 (i) [styrene ] 3 i 7 [methacrylic acid] 2 5 6 (i)
- [Methyl methacrylate] 620 [sodium acrylate] 620 (i, tetrahydrofuran).
- the block polymers I, II suitable as ⁇ amphiphilic substances to be added according to the invention are obtainable, for example, by anionically initiated sequential polymerization (“living polymers”). Instead of the unsaturated organic acids such as acrylic acid and methacrylic acid, they are often initially tert. -Butyl ester copolymerized and subsequently converted into the acid form by hydrolysis. In a similar manner, the acid anhydrides are also partially copolymerized instead of the acids and subsequently hydrolyzed.
- the block polymers I, II are preferably prepared, however, by the radical-initiated sequential polymerization, i.e. on pseudo-living radical polymers as described in US-A 4,581,429, US-A 5,322,912 and US-A 5,412,047.
- the key of the procedure disclosed in these documents consists in the radical-initiated polymerization in the presence of stable radicals, e.g. N-oxyl radicals, which leads to polymers which can be reactivated to form radical polymers and can thus continue to grow after the addition of further monomers.
- N-oxyl radicals examples include: 2,2,6,6-tetramethyl-1-pyrrolidinyloxy (TEMPO), 4-oxo-2,2,6,6-tetramethyl-l-piperidinyloxy (4-oxo -TEMPO), 4-hydroxy-2,2,6, 6-tetramethyl-1-piperidinyloxy, 2,2,5,5-tetramethyl-1-pyrrolidinyloxy, 3-carboxy-2,2,5, 5-tetramethyl- pyrrolidinyloxy and di-tert. -butyl nitroxide.
- TEMPO 2,2,6,6-tetramethyl-1-pyrrolidinyloxy
- 4-oxo-2,2,6,6-tetramethyl-l-piperidinyloxy (4-oxo -TEMPO)
- 4-hydroxy-2,2,6, 6-tetramethyl-1-piperidinyloxy 2,2,5,5-tetramethyl-1-pyrrolidinyloxy
- 2,6-diphenyl-2,6-dimethyl-1-piperidinyloxy and 2,5-dephenyl-2, 5-dimethyl-1-pyrrolidinyloxy can also be used. Mixtures of the aforementioned compounds can of course also be used.
- the sequential radical polymerization is generally carried out at elevated temperature, advantageously at 100 to 180 ° C., preferably 110 to 175 ° C., in particular 130 to 160 ° C. It can be carried out both in bulk and in solution (or also by the free-radical aqueous emulsion polymerization method).
- conventional free radical initiators 2, 4-dimethyl-2,5-dibenzyl-peroxyhexane, tert. Butyl peroxybenzoate, di-tert.
- butyl diperoxyphthalate Methyl ethyl ketone peroxide, dicumyl peroxide, tert. -Butyl-peroxycroto ⁇ - nat, 2,2-bis-tert. -butyl (peroxybutane), tert. -Butylperoxy-isopropyl carbonate, 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane, tert. - Butyl peracetate, di-tert. -butyl-diperoxyphthalate, 2,4-pentadiene peroxide, di-tert.
- Particularly suitable conventional radical initiators to be used are those with a half-life of approx. 1 h at temperatures of 60 to 90 ° C.
- the molar ratio of N-oxyl radical: conventional free radical initiator should be 0.5 to 5, preferably 0.8 to 4. In this way, values of 1 to 3 or 1 to 2, usually 1 to 1.5, frequently 1 to 1.2 and often 1 to 1.1 can be achieved for U.
- Block polymers with U values in the abovementioned ranges are generally suitable according to the invention.
- N-oxyl radicals instead of starting from stable N-oxyl radicals, it is also possible to start from compounds (e.g. the alkoxyamines of US Pat. No. 4,581,429) which e.g. decompose under the action of heat to form a stable N-oxyl radical and a radical partner initiating the polymerization.
- Such N-oxyl radicals can also be generated in situ from suitable compounds having an NO function (cf. column 5, lines 60 ff of US Pat. No. 4,581,429).
- Block polymers with a molecular weight that is as uniform as possible are advantageous according to the invention in that the micelles in their micellar aqueous solutions generally have an essentially uniform size, which, when used for controlled free-radical aqueous emulsion polymerization, results in the production of essentially monodisperse (with respect to the
- Micellar aqueous solutions of the amphiphilic substances to be added according to the invention with a broad micelle size distribution can be used as such for the controlled free-radical aqueous emulsion polymerization (generally resulting in aqueous polymer dispersions with a broader polymer particle diameter distribution) and (because of their long lifetimes) previously in the analytical ultracentrifuge fractionated according to their size and are only used as such monodisperse portions for their use according to the invention.
- Another possibility of fractionation is offered by the flow field - flow fractionation, which sorts according to the micellar hydrodynamic diameter. A representation of this fractionation method can be found, for example, in Anal. Chem. 1992, 64, 790-798.
- the ratio of M w / M n is a measure of the quality of the fractionation.
- the micellar weight-average molecular weight provides, for example, classic light scattering, and the micellar number-average molecular weight is available, for example, by membrane osmometry.
- block polymers to be used according to the invention are produced by initiated polymerization.
- hydrophobic block can also be terminated in this way.
- the process according to the invention for the preparation of an aqueous polymer dispersion by polymerizing monomers having at least one vinyl group by the free-radical aqueous emulsion polymerization method can be carried out in a simple manner by adding a micellar aqueous solution to the additive according to the invention in a polymerization vessel amphiphilic substance, optionally further aqueous dispersion medium, the monomers to be polymerized and the radical polymerization initiator mixed with one another, the mixture heated to the polymerization temperature with stirring and the polymerization maintained with stirring until the desired polymerization conversion.
- the polymerization temperature normally ranges between 20 and 100 ° C. It is often 50 to 45 95 ° C and often it is 70 to 90 ° C.
- the free radical aqueous emulsion polymerization is usually carried out at atmospheric pressure (1 atm). However, particularly when using monomers which are gaseous at normal pressure, it can also take place under elevated pressure. In a corresponding manner, polymerization temperatures above 100 ° C. are also possible (for example up to 130 ° C.). The conditions mentioned above are also typical of the other processes of free-radical aqueous emulsion polymerization dealt with in this document.
- the size of the polymer particles formed is essentially determined by the type and amount of the amphiphilic substance to be added according to the invention contained in the batch. With increasing amount of the amphiphilic substance contained in the batch, smaller polymer particles are achieved and vice versa. A doubling of the amount of the relevant amphiphilic substance contained in the polymerization batch is normally accompanied by a doubling of the number of polymer particles formed which are in a disperse distribution.
- a disadvantage of the emulsion polymerization method described is that it is only suitable for the preparation of aqueous polymer dispersions with a relatively low polymer content.
- the polymerization method with the total batch consists e.g. Problems regarding the technical controllability of the removal of the exothermic heat of the polymerization reaction.
- the radical aqueous emulsion polymerization is therefore generally carried out using the feed process. That is, the predominant amount (usually 50 to 100% by weight) of the monomers to be polymerized is added to the polymerization vessel in accordance with the progress of the polymerization of the monomers already in the polymerization vessel (polymerization conversion generally ⁇ 80 or ⁇ 90 or> 95 mol%) added.
- a micellar aqueous solution of the amphiphilic substance to be added according to the invention is usually placed in the polymerization vessel in the feed process according to the invention.
- the quantitative ratio of the micelles (and their type) and the monomers to be polymerized essentially determines the size of the polymer particles in the resulting aqueous polymer dispersion.
- up to 20% by weight of the monomers to be polymerized are preferably also introduced into the polymerization vessel.
- the remaining monomers are fed in within the feed process according to the invention in such a way that at any point in time the polymerization conversion of the monomers already previously supplied to the polymerization vessel in total is at least 80 mol%, preferably at least 90 mol%.
- the manner in which the radical initiator system is added to the polymerization vessel in the feed process in the course of the radical aqueous emulsion polymerization according to the invention is of minor importance.
- the initiator system can either be completely introduced into the polymerization vessel or, depending on its consumption, can be added continuously or in stages in the course of the feed process according to the invention. Specifically, in a manner known per se to the person skilled in the art, this depends both on the chemical nature of the initiator system and on the polymerization temperature.
- the amphiphilic substance to be added according to the invention is added to the polymerization vessel or only during the monomer feed (ie, the initial charge does not include its total amount), this generally results in a controlled broadening of the size distribution of the resulting polymer particles .
- the amphiphilic substance to be added according to the invention is preferably also supplied here in the form of a prefabricated micellar aqueous solution.
- DE-A 42 13 969, DE-A 42 13 968, DE-A 42 13 967, DE-A 42 13 964 and DE-A 42 13 965 are applied in a transferable manner to suitably highly concentrated aqueous To produce polymer dispersions.
- the aqueous starting dispersions to be used in the above-mentioned published documents are to be replaced in a simple manner by corresponding micellar aqueous solutions according to the invention.
- Suitable radical polymerization initiators for the process according to the invention are all those which are capable of triggering a radical aqueous emulsion polymerization.
- peroxides for example alkali metal peroxidisulfates, as well as azo compounds.
- azo compounds for example azo compounds.
- Butyl hydroperoxide or alkali metal peroxide sulfates and / or ammonium peroxidisulfate can be used.
- a water-soluble iron (II) salt instead of a water-soluble Fe (II) salt, a combination of water-soluble Fe / V salts is often used.
- the amount of free-radical initiator systems used based on the total amount of the monomers to be polymerized, is 0.1 to 2% by weight.
- the process according to the invention does not necessarily require the use of additional dispersants in order to obtain an aqueous polymer dispersion of satisfactory stability.
- aqueous polymer dispersions which are free of further dispersants and obtainable by the process according to the invention are advantageous in that they have a particularly low tendency to foam and a comparatively high surface tension.
- conventional dispersants can also be used in the process according to the invention for the purpose of further stabilizing the disperse distribution of the polymer particles produced.
- additional dispersants if additional dispersants are also used, care must be taken to ensure that the amounts are measured in such a way that the cmc 's of these additional dispersants are not exceeded. It is often advisable to post-stabilize after the radical aqueous emulsion polymerization according to the invention has ended by adding conventional dispersants. Examples of such conventional dispersants are the classic surfactants.
- Examples include Dowfax ® 2Al from the Dow Chemical Company, ethoxylated mono-, di- and tri-alkylphenols (EO grade: 3 to 50, alkyl radical: C 4 to C 9 ), ethoxylated fatty alcohols (EO grade: 3 to 50, alkyl radical: Cs to C 36 ), and alkali and ammonium salts of alkyl sulfates (alkyl radical: CQ to C ⁇ 2 ), of sulfuric acid semiesters of ethoxylated alcohols (EO degree: 4 to 30, alkyl radical: C ⁇ 2 to Ci ⁇ ) and ethoxylated Alkylphenols (EO grade: 3 to 50, alkyl radical: C 4 to C 9 ), of alkyl sulfonic acids (alkyl radical: C i2 to Cis) and of alkylarylsulfonic acids (alkyl radical: C 9 to Ci ⁇ ).
- EO grade: 3 to 50, alkyl radical: C 4 to C 9 alkyl
- surfactants can be found in Houben-Weyl, Methods of Organic Chemistry, Volume XIV / 1, Macromolecular Substances, Georg-Thieme Verlag, Stuttgart, 1961, pages 192 to 208.
- conventional protective colloids can also be used such as polyvinyl alcohol, polyvinylpyrrolidone or amphiphilic block polymers with short hydrophilic blocks are used for co-stabilization.
- the amount of conventional dispersants used, based on the monomers to be polymerized, will not exceed 3 or 2% by weight.
- Suitable radically polymerizable monomers for the process according to the invention are, in particular, monoethylenically unsaturated monomers such as olefins, e.g. Ethylene, vinyl aromatic monomers such as styrene, ⁇ -methylstyrene, o-chlorostyrene or vinyl toluenes, vinyl and vinylidene halides such as vinyl and vinylidene chloride, esters of vinyl alcohol and monocarboxylic acids such as vinyl acetate, vinyl propionate containing 1 to 18 carbon atoms, Vinyl n-butyrate, vinyl laurate and vinyl stearate, esters of ⁇ , ⁇ -monoethylenically unsaturated preferably having 3 to 6 carbon atoms
- monoethylenically unsaturated monomers such as olefins, e.g. Ethylene
- vinyl aromatic monomers such as styrene, ⁇ -methylstyrene,
- Mono- and dicarboxylic acids such as, in particular, acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid, with alkanols which generally have 1 to 12, preferably 1 to 8 and in particular 1 to 4, carbon atoms, such as, in particular, methyl methyl acrylate and methacrylic acid -, -ethyl, -n-butyl, -iso-butyl and -2-ethyl-hexyl ester, maleic acid dimethyl ester or maleic acid n-butyl ester, nitriles ⁇ , ⁇ -monoethylenically unsaturated carboxylic acids such as acrylonitrile and C 4 - 8 conjugated dienes such as 1,3-butadiene and isoprene.
- alkanols which generally have 1 to 12, preferably 1 to 8 and in particular 1 to 4, carbon atoms, such as, in particular, methyl methyl acrylate and methacrylic
- the monomers mentioned generally form the main monomers, which, based on the total amount of the monomers to be polymerized by the free-radical aqueous emulsion polymerization process according to the invention, normally comprise more than 50% by weight.
- Monomers which, when polymerized, usually give homopolymers which have an increased solubility in water are normally only used as modifying monomers in amounts, based on the total amount of the monomers to be polymerized, of a few less than 50 wt .-%, usually 0.5 to 20, preferably 1 to - 10 wt .-%, co-polymerized.
- Examples of such monomers are ⁇ , ⁇ -monoethylenically unsaturated mono- and dicarboxylic acids and their amides such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, acrylamide and methacrylamide, also vinylsulfonic acid and its water-soluble salts and N- Vinyl pyrrolidone.
- Monomers which usually increase the internal strength of the films in the aqueous polymer dispersion, are generally also co-polymerized only in minor amounts, usually 0.5 to 10% by weight, based on the total amount of the monomers to be polymerized.
- Such monomers normally have an epoxy, hydroxyl, N-methylol, carbonyl groups or at least two non-conjugated ethylenically unsaturated double bonds.
- N-alkylolamides of ⁇ , ⁇ -monoethylenically unsaturated carboxylic acids having 3 to 10 C atoms and their esters with alcohols having 1 to 4 C atoms including the N-methylol-acrylamide and the N-methylol-methacrylamide entirely particularly preferred are silanized monomers such as ⁇ -methacryloxypropylsilane or vinyltrimethoxysilane, two monomers containing vinyl residues, two monomers containing vinylidene residues and two monomers having alkenyl residues.
- the di-esters of dihydric alcohols with ⁇ , ⁇ -monoethylenically unsaturated monocarboxylic acids are particularly suitable, among which in turn acrylic and methacrylic acid are preferably used.
- monomers having two non-conjugated ethylenically unsaturated double bonds are alkylene glycol diacrylates and dimethacrylates such as ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butylene glycol diacrylate and propylene glycol diacrylate, divinylbenzene, allyl methacrylate acrylate, vinyl methacrylate acrylate , Methylenebisacryamide, cyclopentadienyl acrylate or triallyl cyanurate.
- methacrylic acid and acrylic acid-Ci-C ⁇ -hydroxyalkyl esters such as hydroxyethyl, n-hydroxypropyl or n-hydroxybutyl acrylate and methacrylate, and compounds such as diacetone acrylamide and acetylacetoxyethyl acrylate or methacrylate.
- minor amounts usually 0.01 to 2% by weight, based on the monomers to be polymerized, can also be used to copolymerize substances which regulate the molecular weight, such as tert-dodecyl mercaptan and 3-mercaptopropyltrimethoxysilane.
- Such substances are preferably added to the polymerization zone in a mixture with the monomers to be polymerized.
- such monomer mixtures can be polymerized in a controlled manner by the free-radical aqueous emulsion polymerization method to give aqueous polymer dispersions which contain 5 to 70 to 100% by weight of esters of acrylic and / or methacrylic acid with 1 to 12 ° C. -Atomic alkanols and / or styrene or
- the acrylate mixtures in particular also include the following monomer compositions, which consist of:
- Methacrylic acid with alkanols containing 1 to 8 carbon atoms Methacrylic acid with alkanols containing 1 to 8 carbon atoms
- aqueous polymer dispersions resulting according to the invention are used both as binders (for example paper coating slips, interior paints, fiber mats) and as adhesives or Additives in mineral setting, eg cementitious, masses are suitable.
- the method according to the invention is normally carried out under inert gas and with stirring.
- the amount of amphiphilic substance added according to the invention is 0.1 to 15, preferably 0.5 to 6,% by weight, based on the monomers to be polymerized.
- the micellar number in the aqueous solution can be calculated from the micellar molecular weight 10 (e.g. determined from the sedimentation run of the analytical ultracentrifuge or by means of classic light scattering) and the initial weight, thus determining the desired number of polymer particles in advance.
- the solid volume concentration of aqueous polymer dispersions obtainable according to the invention is 10 to 70% by volume, or 25 to 70% by volume, or 35 to 70% by volume or 45 to 70% by volume can be.
- the resulting number average polymer particle diameter can range from 10 to
- auxiliaries can be dried to redispersible polymer powders (e.g. freeze drying or spray drying). This is particularly true when the glass transition temperature of the added amphiphilic substance is 60 60 ° C, preferably> 70 ° C, particularly preferably> 80 ° C and very particularly preferably> 90 ° C or 0> 100 ° C. It will normally not exceed 250 ° C.
- Tetrahydrofuran (Riedel de Haen, chromasolv) was dried by adding n-butyllithium (the end point was indicated by means of styrene; remaining, not hydrolyzed n-butyllithium triggers anionic polymerisation of the styrene; the intense red color of it emerging styrene macro anions acts as an indicator) and degassed by multiple vacuum pulls. After drying was complete, 90 ml of tetrahydrofuran was distilled off in vacuo and the last 0 2 traces were removed by freezing, vacuuming and thawing three times.
- Methyl methacrylate and subsequent molecular weight determination of the polymer formed were determined by means of gel permeation chromatography.
- Triethylaluminum (as a 15% strength by weight solution in hexane, from Fluka, purum) was added until a noticeable yellow color occurred (this was the case after the addition of 2.4 ml of the hexane solution). Then vacuum was again drawn briefly and finally 2/3 of pure monomer was distilled off under vacuum, frozen and vacuum was drawn again.
- hydrophilic block polymers BP2 to BP7 were produced in a corresponding manner:
- the surface tension was determined using a ring tensiometer from Lauda (TElc) at 20 ° C and 1 atm.
- the aqueous solutions investigated were obtainable directly. The results obtained are shown in Table 1 below.
- FIG. 1 shows a graphical representation of the results. It shows that the sodium salts of BP8, BP7, BP6 and BP5 are not amphiphilic substances according to the invention. In particular the Na salt of BP8 behaves like a classic surfactant. Similar results as for the Na salts were obtained for the ammonium salts.
- dso values 50% by weight of the polymer has a particle diameter> .dso and 50% by weight of the polymer has a particle diameter ⁇ dso on
- Tables 2 and 3 below show the compositions of feed, feed 1 and feed 2 and the d 50 values of the resulting aqueous polymer dispersions.
- Inlet 2 water 60 60 60 60 60 60 60 60 60 60 60 60 60 60 60
- the number of polymer particles formed is inversely proportional to the third power of the particle diameter.
- Figures 2 and 3 show a graphic representation of (l / d 3 50 ) -IO 7 [nm -3 ] of the dso values listed in Tables 2 and 3 as a function of the amount of BP1 and BP8 added for the polymerization.
- FIG. 3 shows an almost constant number of polymer particles formed in the range of small amounts of BP8 added. This is attributed to the fact that, with an increasing amount of added BP8, the number of micelles presented increases, but the latter are not initiated quantitatively, but some of them dissolve in the other part in the course of the formation of polymer particles, in order to prevent this Stabilizing polymer particle growth in the same (if the polymerizations were not carried out according to the feed procedure, but all components were introduced in a mixture and then heated to the reaction temperature, essentially identical results were obtained). 4) Investigations of aqueous solutions of the ammonium salt of BP1 - and aqueous polymer dispersions containing this salt with the analytical ultracentrifuge
- Aqueous solutions were investigated, each containing 6, 3, 2 or 1 g of BP1 per liter and 0.4 g of a 25 wt. -.Aqueous NH 3 solution contained. Furthermore, the aqueous solutions examined contained 0.1 mol of NH 4 C1 per liter in order to facilitate the dissociation of polyanion and ammonium ions in the centrifugal field.
- the test temperature was 20 ° C. In all cases, only a unimodal streak peak occurred in the sedimentation run (40,000 revolutions per minute).
- the sedimentation rate was 7.2 Svedberg in all cases. The level of the sedimentation rate indicated that the sedimenting units must not be BP1 unimers but aggregates of the same, which indicates the micellar character of the aqueous solutions examined.
- the streak peak of the unimeric BPl also contained at least 99% of the subsequently added amount of BPl after this time.
- the amphiphilic block copolymer did not attach to the dispersed polymer particles, and its micellar solution was retained.
- a steel solution of 1 g BPl, 0.4 g 25% by weight NH 3 solution and 300 g water was prepared, which was diluted by means of a 0.1 molar aqueous NH 4 Cl solution.
- the concentration-dependent course shows (no turning to higher reciprocal values with increasing dilution) that the cmc is not reached even with a dilution to 10 7 mol / 1.
- di-block polymers of comparable composites Composition covalently labeled once with the donor naphthalene and once with the acceptor pyrene:
- both di-block polymers were used to produce aqueous solutions of their Na salt (dissolve the block polymer in water containing NaOH) which, in addition to water, contained per liter of solution:
- the ammonium salts of the di-block copolymers a) to d) were used for free-radical aqueous emulsion polymerization as follows: The monomers (in a mixture of 50% by weight of n-butyl acrylate and 50% by weight of methyl methacrylate), water, 0.5% by weight of sodium peroxodisulfate (based on the monomers) and X pphm (based on the weight of the monomers) of the aforementioned ammonium salts were mixed with one another and heated to the polymerization temperature of 90 ° C. with stirring and polymerized at this temperature up to a conversion of> 99% by weight (selected solids content: 30% by weight). In all cases, aqueous polymer dispersions with sufficient stability were obtained.
- the Xpphm used were: 1 pphm di-block copolymer a) 1 pphm di-block copolymer b) 2 pphm di-block copolymer b)
- the light transmittance (an indirect measure of the polymer particle size) of the aqueous polymer dispersions was> 91 in all cases.
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Abstract
Description
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US09/101,778 US6218468B1 (en) | 1996-01-25 | 1997-01-23 | Preparation of an aqueous polymer dispersion by the free radical aqueous emulsion polymerization method |
EP97902206A EP0876404B1 (de) | 1996-01-25 | 1997-01-23 | Verfahren zur herstellung einer wässrigen polymerisatdispersion nach der methode der radikalischen wässrigen emulsionspolymerisation |
DE59709787T DE59709787D1 (de) | 1996-01-25 | 1997-01-23 | Verfahren zur herstellung einer wässrigen polymerisatdispersion nach der methode der radikalischen wässrigen emulsionspolymerisation |
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DE19602538A DE19602538A1 (de) | 1996-01-25 | 1996-01-25 | Verfahren zur Herstellung einer wäßrigen Polymerisatdispersion nach der Methode der radikalischen wäßrigen Emulsionspolymerisation |
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US6713552B1 (en) * | 1999-08-23 | 2004-03-30 | Rohm And Haas Company | Pressure sensitive adhesive with improved peel strength and tack |
WO2005082912A1 (en) * | 2004-02-23 | 2005-09-09 | Dow Global Technologies Inc | Aqueous-based adhesive for bonding low surface energy substrates |
FR2880024B1 (fr) * | 2004-12-23 | 2007-02-02 | Arkema Sa | Utilisation de copolymeres a gradient de composition comme stabilisants dans la polymerisation radiculaire en emulsion |
US10329372B2 (en) * | 2014-06-13 | 2019-06-25 | Basf Se | Polyurethanes with reduced aldehyde emission |
CN107810204B (zh) | 2015-06-17 | 2020-04-14 | 巴斯夫欧洲公司 | 用于立即终止自由基聚合的组合物 |
CN116490535A (zh) | 2020-11-30 | 2023-07-25 | 巴斯夫欧洲公司 | 制备聚合物分散体的方法 |
EP4230289A1 (de) | 2022-02-16 | 2023-08-23 | CHT Turkey Kimya Sanayi ve Ticaret A.S. | Emulsionspolymerisations-managementsystem (epm) durch proportionales heizen/kühlen und durchflussregelung für gleichbleibende produktqualitäten |
WO2024073633A2 (en) * | 2022-09-30 | 2024-04-04 | Diaz Jairo A | Precise size and shape control of colloids using temperature-active block-copolymer micelles |
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EP0597567A2 (de) * | 1992-11-13 | 1994-05-18 | Rohm And Haas Company | Verfahren zur Herstellung von grosser Emulsion Polymer Artikeln, Polymer Produkt und seine Verwendung |
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US3251905A (en) | 1963-08-05 | 1966-05-17 | Phillips Petroleum Co | Method of preparing block copolymers of conjugated dienes and vinyl-substituted aromatic compounds using dilithio catalysts and diluent mixture of hydrocarbon and ether |
US3390207A (en) | 1964-10-28 | 1968-06-25 | Shell Oil Co | Method of making block copolymers of dienes and vinyl aryl compounds |
US3598887A (en) | 1966-02-26 | 1971-08-10 | Polymer Corp | Preparation of block copolymers |
FR2227568B1 (de) | 1972-09-18 | 1976-11-12 | Rank Xerox Ltd | |
US4385164A (en) * | 1976-03-10 | 1983-05-24 | The Goodyear Tire & Rubber Company | Block copolymer dispersion stabilizer and aqueous dispersion polymerization therewith |
AU546371B2 (en) | 1980-05-21 | 1985-08-29 | Dow Chemical Company, The | Heterogeneous polymer latex |
DE69305044T3 (de) | 1992-03-02 | 2000-08-24 | Du Pont | Anionoschen farbstoff enhaltende tintenstrahldrucktinte |
ATE164596T1 (de) | 1994-01-28 | 1998-04-15 | Goldschmidt Ag Th | Polymethacrylat-polymethacrylsäure- blockcopolymere |
US5484681A (en) | 1994-10-31 | 1996-01-16 | Xerox Corporation | Conductive composite particles and processes for the preparation thereof |
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1996
- 1996-01-25 DE DE19602538A patent/DE19602538A1/de not_active Withdrawn
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1997
- 1997-01-23 US US09/101,778 patent/US6218468B1/en not_active Expired - Fee Related
- 1997-01-23 DE DE59709787T patent/DE59709787D1/de not_active Expired - Fee Related
- 1997-01-23 EP EP97902206A patent/EP0876404B1/de not_active Expired - Lifetime
- 1997-01-23 WO PCT/EP1997/000308 patent/WO1997027222A1/de active IP Right Grant
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
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US4219627A (en) * | 1977-03-09 | 1980-08-26 | The Firestone Tire & Rubber Company | Process for the preparation of block copolymers |
EP0597567A2 (de) * | 1992-11-13 | 1994-05-18 | Rohm And Haas Company | Verfahren zur Herstellung von grosser Emulsion Polymer Artikeln, Polymer Produkt und seine Verwendung |
Also Published As
Publication number | Publication date |
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EP0876404A1 (de) | 1998-11-11 |
US6218468B1 (en) | 2001-04-17 |
EP0876404B1 (de) | 2003-04-09 |
DE19602538A1 (de) | 1997-07-31 |
DE59709787D1 (de) | 2003-05-15 |
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